Management of the Developing Occlusion

Question 1

Where are primate spaces found?

Answer 1

max: between lateral/canine
mand: between canine/1st molar

Question 2

when does transverse widening of the intercanine width of the max and mand arches occur? By how much?

Answer 2

during eruption of permanent incisors.

the mean increase in intercanine width is 3-4mm in max and 2-3mm in mand.

Question 3

T or F. About 40% of arches w/o primary dental spacing result in crowded anterior segments.

Answer 3

True.

Question 4

by what age are the incisor alignment patterns and intercanine arch dimensions essentially established?

Answer 4

age 8.

Therefore, interceptive procedures receive significantly more emphasis in this period to allow for a harmonious transition directed toward achieving alignment of the permanent incisors and 6yr molars with symmetric arch development and coincident midlines.

Question 5

What are the leeway spaces?

Answer 5

• 1.7mm each side on mandible (total: 3.4mm mand arch)

- 0.9mm each side on maxilla (total: 1.8mm max arch)

Question 6

If premature space loss and no space maintenance is used, up to how many mm per quad will you lose in the maxilla? Mandible?

Answer 6

up to 8mm per max quad and up to 4mm per mand quad

Question 7

T or F. Space loss potential is particularly high if the primary molar loss occurs in approximation to first permanent molar eruption, irrespective of which primary molar is lost and in which arch the loss occurs.

Answer 7

True

Question 8

What is the direction of closure of maxillary posterior spaces if space loss? Mandibular spaces?

Answer 8

mesial bodily movement and ML rotation in maxillary posterior spaces whereas in mandibular spaces, you’ll see mesial tipping of posterior teeth (with tendency to roll lingually) along with distal movement and retroclination of anterior teeth

Question 9

How much of the root is developed when teeth normally erupt?

Answer 9

When 3/4th the root is developed.

Question 10

If there is loss of a primary molar before the age of 7, would you have delayed or early emergence of the succedaneous tooth?

Answer 10

if premature primary molar loss before age 7, expect delayed succedaneous emergence. If after 7, expect early emergence.

Question 11

How long does it take for premolars to move through 1mm of bone for eruption?

Answer 11

4-6 months

Question 12

What are we assessing for in the primary dentition stage?

Answer 12

1. all anomalies of tooth numbers/size
2. anterior or posterior x-bites
3. presence of habits along with their dental/skeletal sequelae
4. open bite
5. airway problems

Question 13

What are we assessing for in the early mixed dentition stage?

Answer 13

same as what we were assessing in primary dentition stage but also unerupted teeth, positions of teeth erupting suc has ectopic 6s, developing skeletal discrepancies, perio health

Question 14

What are we assessing for in the late mixed dentition stage?

Answer 14

everything that we evaluate for in early mixed but with an emphasis on evaluation for ectopic tooth positions, esp canines, premolars, and second perm molars.

Question 15

By what age would we want non-nutritive sucking habits to stop?

Answer 15

36months of age (3yrs old)

Question 16

T or F. Tongue thrusting may be associated with anterior open bite, abnormal speech, and anterior protrusion of the maxillary incisors.

Answer 16

True

Question 17

T or F. If the resting tongue posture is forward of the normal position, incisor displacement is likely. If resting tongue posture is normal, incisor displacement is also likely.

Answer 17

False.
The first statement is true but the second statement is false.
If resting tongue posture is normal, a tongue thrust swallow has no clinical significance.

Question 18

What are the most commonly missing permanent teeth? Primary teeth?

Answer 18

MC missing permanent teeth: 3rds>mand 2nd pre>max laterals>max 2nd pre

MC missing primary teeth: max incisors and 1st primary molars

Question 19

Which arch more commonly has supernumerary teeth? In which area? And in what direction?

Answer 19

• Max>mand (about 80-90% of all supernumeraries occur in maxilla)
• MC max anteriors
• displaced in palatal position

Question 20

If a child has an unerupted supernumerary tooth (ie mediodens), at what dentition stage is it most advantageous to EXT it?

Answer 20

extraction of an unerupted supernumerary during the EARLY MIXED dentition (~6-7yo, when perm tooth has formed completely and root length is LESS than crown height) allows for a normal eruptive force and eruption of the adj normal permanent incisor.

later removal of mesiodens reduces likelihood that the adj normal perm incisor will erupt on its own, esp if apex is completed

Question 21

There are two types of ectopic eruptions. Those that self-correct and those that remain impacted.
About what percentage of ectopically erupting teeth self correct? And if so, by what age?

Answer 21

about 66% (2/3) of ectopically erupting teeth will self-correct by age 7.

Question 22

What are some indications that there needs to be early intervention of ectopically erupting teeth (vs watching and waiting for it to self correct)?

Answer 22

1. increased magnitude of impaction
2. increased resorption of primary tooth
3. bilateral occurrence are associated with IRREVERSIBLE ectopic eruption
4. asymmetric arch development–including supra-eruption of opposing dentition

Question 23

What clinical findings would make you suspect an impacted max canine? Radiographically?

Answer 23

1. when canine bulge is not palpable
2. asymmetry canine eruption is evident
3. peg shaped lateral incisors are present

Radiographically:

1. canine has abnormal inclination and/or overlaps lateral incisor root
2. enlarged follicular sac
3. lack of root resorption of primary canines
4. presence of premolar impaction

Question 24

When would you suspect ectopic eruption of permanent incisors?

Answer 24

• after trauma to primary incisors
• with pulpally-treated primary incisors
• asymmetry eruption
• if supernumerary incisor is dx

Question 25

What are some tx options for impacted max canines?

Answer 25

RPE and/or cervical pull headgear in early mixed dentition has been shown to increase the potential for eruption of palatally-displaced maxillary canines. When the impaction is diagnosed at a later stage (11-16yo), if canine is not horizontal, EXT of primary canine lessen the severity of perm canine impaction and 75% will erupt!
Extraction of first primary molar has also been interrupted to allow eruption of first premolars and to assist in the eruption of the canines.

Question 26

Ankylosis is most commonly associated with which teeth?

Answer 26

primary molars, although it can occur in both primary and permanent dentitions.

If it occurs in permanent dentition, typically after luxation injuries. Common in anterior teeth following trauma and referred to as REPLACEMENT RESORPTION.

Question 27

How can you dx ankylosis?

Answer 27

Clinically: submergence of tooth, percussion, palpation
Rx: loss of PDL, bony bridging

Question 28

An overject in excess of __mm is associated with an increased risk of incisor injury, with large overjets (>___mm) resulting in trauma in more than __% of children

Answer 28

1. 3mm
2. 8mm
3. 40%

Question 29

Of the three molar terminal plane relationships, which is the most common to least common?

Answer 29

FTP>MS>DS

Question 30

What is early mesial shift and when does it occur?

Answer 30

Early mesial shift occurs when the interdental spacings close between molars PRIOR to the eruption of the 6s,. This occurs at approximately at age 4.

this closing of interdental spacings occurs due to eruption path of perm molars, which guide on distal roots of primary second molars, thereby closing space.

Question 31

In eruption and sequencing, what is the most common eruption sequence of the arches? What is the most common variation to this?

Answer 31

mand arch: 6-1-2-4-5-7
max arch: 6-1-2-4-3-5-7
this occurs 50% of the time

MC variation: 2nd molars erupt in either arch prior to more anterior teeth

Question 32

At what age is incisor transition complete to establish mixed dentition stage?

Answer 32

age 8. when pt has 6s along with incisors and the C-D-E primary teeth.

• *mand canines erupt around age 10
• *max/mand 1st premolars erupt around age 11-11.5
• *max/mand 2nd premolars erupt around age 11.5-12
• *max canines erupt at around age 12+

Question 33

During transition from primary incisors to permanent incisors, there is an increase in intercanine arch width. By how much does it increase?

Answer 33

the max arch will inc by about 3mm and mand arch will inc by about 2.4mm.

Question 34

MC ankylosed tooth

Answer 34

mand 1st primary molar»>max 1st primary molar>mand second primary molar>max 2nd primary molar

Question 35

In terms of eruption guidance, when there is incisor crowding, when do you disk primary canines vs prophylactically extract them to make space?

Answer 35

if incisor crowding is <3-4mm and the primary canine roots are intact, disc the ML corner of the primary canines to provide “sluice way” for incisor alignment, ESP if pt has deepbite patterns.

if incisor crowding is >4mm, extract primary canines, esp to help with midline symmetry and if pt has dolichofacial openbite pattern.